Zeppelins were coming to London, Thomas wrote to Frost on 1 June. The capital was bombed the night before and gripped now by the panic buying of gas masks. Air strikes were a new threat for the British people: they had begun along the east coast in January but had been sporadic and ineffectual; now the airships were coming for the cities, spreading terror as they went. Helen worried about her husband's visits to town, but Edward had not needed to travel to London since he began writing up The Life of the Duke of Marlborough in May. By 19 June, the book was finished. Thomas celebrated with a week's cycling that led him up to Jack Haines's house at Hucclecote in Gloucestershire, where he wrote a confessional lyric, opening:

I built myself a house of glass:
It took me years to make it:
And I was proud. But now, alas,
Would God someone would break it.

Thomas had found joy in childhood throwing stones 'over into the unknown depths of a great garden and hearing the glasshouse break'. He longed for someone to break through the edifice that he had put around himself, an edifice designed, he said, to protect his humility. To Edward Garnett he explained that any 'superiority' that his friend detected was nothing more than a self-defence, prone to thickening into a 'callosity'. More than anything, he missed Frost's companionship, a feeling that was only deepened by his walks that week with Haines around Dymock, when the two men had talked about Frost as they strode. Frost alone among his friends had taken him by the scruff of the neck and urged better things from him: he had been the one man willing to throw stones, to 'kick' the nonsense out of him. Helen and Eleanor were too much in awe of Thomas—or feared too much his rebuke—to take on such a bullish role, but not Frost, who had urged Thomas not to judge himself with such harshness. 'I can't help it,' had been Thomas's response, 'but I can help personally-conducted tours to the recesses.' It was a new realisation from Thomas: that he might now be able to control his descent into the worst areas of his depression.

Haines and Thomas climbed May Hill together that visit, though not to the crown of fir trees that ringed the summit where he had walked the previous summer with Frost. He began 'Words', a poem set on the great hillside: 'Out of us all / That make rhymes, / Will you choose / ... / Choose me, / You English words?' Everything now was revolving around Thomas's quarrel with himself whether or not to write poetry, go to America, enlist. Money was tighter than ever. 'It is wretched to be willing to work, to think I know what I can do, and yet not to be sure of £150 a year,' he told Eleanor. 'If anybody said You go and join the Royal Garrison Artillery and they will give you a commission, I believe I should go next month.' Food prices were a quarter higher than when the war broke out, bread by as much as a half—'and work so much more than 25% scarcer'—and he began to watch more jealously than before as the few remaining bursaries and grants passed him by, some of them given to his friends. 'De la Mare has got £100 a year now from the Civil List, and he was making £400 at least,' he complained to Frost. 'I was annoyed especially as I am told I have no chance myself as being too young and not as well known as many others who will be applying. Let me admit also that I felt they might have let me sign the petition as I have probably reviewed him more than anyone else. That is frank.' Thomas was beginning to lose patience with friends that he had spent years supporting in his reviews—de la Mare in particular, Davies to an extent—friends who showed no sign of returning the encouragement when it came to his own poetry, let alone petitioning on his behalf for a Civil List pension as he had done over the years for others!

America had never seemed so certain, Eleanor Farjeon recalled. Thomas had gone so far as to prepare his mother for the news that he might emigrate. In those early weeks of June his mind seemed all but made up. 'I am thinking about America as my only chance (apart from Paradise),' he wrote to Frost on 14 June, and to Eleanor he said much the same, that 'America is a chance and that I see no other'. In his correspondence he used and reused this word 'chance', as if America were both an opportunity but also a lottery outside his control. Departure to the States would use up what savings he had (enough to last for only four months) and would, he felt certain, sever his ties with the English newspaper editors for good. It would also mean pulling Bronwen out of Bedales, her fees having been subsidised by Helen's occasional teaching there, so the gamble was substantial: was he prepared, he asked himself, to wager his savings 'and leave the rest to chance'? What guarantees did he have? None that he could see. Some people, he acknowledged, would let their faith guide them in their decision, but not Thomas, who was adamant that he was alone when it came to such matters. 'It all comes of not believing. I will leave nothing to chance knowingly.'

Thomas's vacillation was now bordering on comic, and even Helen teased him with a precision of wit not lost upon him. He explained to Frost, 'These last few days I have been looking at 2 alternatives, trying to enlist or coming out to America. Helen points out that I could try America and then enlist if it failed, but not the other way around.' But secretly, Thomas admitted that the venture might not necessarily include Helen. 'We shall certainly not all go to America,' he confessed to Bottomley. 'I should go alone if other things fail.' Would he really cross the Atlantic without his wife and daughters now, after the difficulties that they were beginning to overcome in their relationships? And in a time of war? When he had no income with which to support them? What about that other crossing, of the English Channel to join British soldiers in France? Was the war the more realistic outcome? 'Frankly I do not want to go,' he confessed, 'but hardly a day passes without my thinking I should. With no call, the problem is endless.'

But the problem was not endless, for a poem of Frost's had arrived which would dramatically force Thomas's hand.

THE ROAD NOT TAKEN

Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;

Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,

And both that morning equally lay
In leaves no step had trodden black.
Oh, I kept the first for another day!
Yet knowing how way leads on to way,
I doubted if I should ever come back.

I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I—
I took the one less traveled by,
And that has made all the difference.

Noble, charismatic, wise: in the years since its composition, 'The Road Not Taken' has been understood by some as an emblem of individual choice and self-reliance, a moral tale in which the traveller takes responsibility for their own destiny. But it was never intended to be read as such by Frost, who was well aware of the playful ironies contained within it, and would go on to warn audiences, 'You have to be careful of that one; it's a tricky poem—very tricky.' Frost knew that reading the poem as straight morality tale would pose a number of difficulties. For one: how can we evaluate the outcome of the road not taken? For another: had the poet chosen the road more travelled by, then that, presumably, would also have made all the difference. Choices might actually be equal, in other words, and Frost had set traps in the very heart of the poem intended to explode a more earnest reading. First he placed a mischievous admission about the wearing of the grass, that along each path 'the passing there / Had worn them really about the same', suggesting that neither was apparently more travelled by. And just in case the trap was missed he set another: 'both that morning equally lay / In leaves no step had trodden black', meaning that there was no discernible difference between the two paths at all. So when the poem culminates in a claim that he took the path less travelled by, it does so with its tongue in its cheek.

'The Road Not Taken' is typical of Frost's skill with perspective and with mirrors: behind the neat, unfussy frontage is an experience of great depth and subtlety, and no small amount of wit. For the poem to appear wise to some and ironic to others is a credit to the sophisticated way in which Frost had become the poet 'for all sorts and kinds': no wonder it stands as such a beguiling poem in the minds of readers; no wonder it has been taken so much to heart. But the poem carried a more personal message besides, 'about a friend who had gone off to war', as he later recalled it, 'a person who, whichever road he went, would be sorry he didn't go the other'. That person was Edward Thomas.

Begun, most likely, at the Gallows in the late autumn of 1914, the poem was set in the woods of Dymock where Frost and Thomas had walked that season and on which Frost now based his mischievous tribute. Two roads diverged in a yellow wood: the much celebrated opening line may itself have been intended as a homage to Thomas, who had opened a 1911 story, 'Three roads meet in the midst of a little green'. (Thomas made Eleanor Farjeon a gift of that story in 1913; it is not beyond possibility that he did the same for Frost.) Many were the occasions when Thomas would guide Frost on the promise of rare wild flowers or birds' eggs, only for the walk to conclude in self-reproach when the path Thomas chose bore no such wonders. Amused at Thomas's inability to satisfy himself, Frost chided him, 'No matter which road you take, you'll always sigh, and wish you'd taken another.' But to Thomas, it was not the least bit funny. It pricked at his confidence, at his sense of fraudulence, reminding him he was neither a true writer nor a true naturalist, cowardly in his lack of direction. And now the one man who understood his indecisiveness most astutely was mocking him for it.

Thomas took the 'tease' badly. He felt the poem to be a rebuke for his own inability to choose between the pursuit of poetry and a career in prose—worse, at his indecisive attitude toward the war, so often expressed to Frost. And he retorted with a sting. 'It's all very well for you poets in a yellow wood to say you choose, but you don't,' he protested. 'If you do, ergo I am no poet. I didn't choose my sex yet I was simpler then. And so I can't leave off going in after myself tho' some day I may. I didn't know after I left you at Newent I was going to begin to write poetry.' Contrary to his understanding of the poem, Thomas was announcing himself as a fatalist, it was clear now. He did not believe in self-determination, or that the spirit could triumph over adversity; some things seemed unavoidable, inevitable. Had he chosen poetry he could not be a poet: as he had written in 'Words', it had in some sense to choose him. How free spirited his friend seemed in comparison. This American who tossed aside his teaching and sailed for England on a long-shot, knowing no one and without a place to go; who rode his literary fortunes and won his prize, then sailed again to make himself a new home. None of this was Thomas. 'It isn't in me.'

It seems curious that Edward Thomas, the man who had understood Frost's writing better than anyone, could not see the poem for what it was. He puzzled at 'the simple words and unemphatic rhythms' which could not, he surmised, lead to great things. 'It staggered me to think that perhaps I had always missed what made poetry poetry if it was here,' he told the American. And he determinedly assured Frost that he had 'got the idea', when plainly he had not.

Frost, a little stung, responded, 'Edward, Methinks you strikest too hard in so small a matter. A tap would have settled my poem. I wonder if it was because you were trying too much out of regard for me that you failed to see that the sigh was a mock sigh, hypocritical for the fun of the thing.' But Thomas saw no such fun: 'You have got me again over the Path not taken & no mistake ... I doubt if you can get anybody to see the fun of the thing without showing them & advising them which kind of laugh they are to turn on.' Frost had already discovered as much on reading the poem before a college audience, where it was 'taken pretty seriously', he admitted, despite 'doing my best to make it obvious by my manner that I was fooling ... Mea culpa.'

A strange but revealing exchange had occurred in which Thomas had exposed something deep within his poetry and his character. And what he had exposed was this: that choice was not, counter to his reading of Frost, an act of free will. Instead, some choices are prescribed, compelled, ingrained in circumstance or personality; some characters are 'called'.

He broke the news to Frost. 'Last week I had screwed myself up to the point of believing I should come out to America & lecture if anyone wanted me to. But I have altered my mind. I am going to enlist on Wednesday if the doctor will pass me.' Thomas made his will, granting Helen its sole execution. On Saturday 10 July he rose early and walked up through the Ashford Hanger to his study where he drafted 'The Brook', in which the poet watched his daughter paddling in the stream, when a butterfly settled on a hot stone, 'as if I were the last of men / And he the first of insects to have earth / And sun together and know their worth.' Thomas had made the same allusion in his prose piece written about his walks with Frost in Dymock, 'This England', of the urgent need to connect—to understand and fight for—the value of the landscape around him. 'Something, I felt, had to be done before I could look again composedly at English landscape,' he wrote then, 'at the elms and poplars about the houses, at the purple-headed wood-betony with two pairs of dark leaves on a stiff stem, who stood sentinel among the grasses or bracken by hedge-side or wood's-edge. What he stood sentinel for I did not know, any more than what I had got to do.' Now, finally, he knew what he had to do. Thomas was passed fit, and the same week, he sat down to lunch with his confidante, Eleanor Farjeon, and informed her that he had enlisted in the Artists Rifles, and that he was glad; he did not know why, but he was glad. Only days before it seemed certain that he would emigrate to America to join Frost, as the two men had planned. And yet suddenly, everything was different. Eleanor would later describe how, in volunteering, the 'self-torment had gone out of him'. And Helen: 'I had known that the struggle going on in his spirit would end like this.'

Thomas explained himself to Frost in a letter. 'To find myself living near you and not working for editors would be better than anything 1 ever did and better than 1 dare expect,' but he could not leave now, he said, not before he had taken the King's shilling: he would have to wait out the war. 'The best way out is always through,' Frost had written in North of Boston, and now Thomas echoed his friend's words as he explained his enlistment: 'It is not my idea of pleasure,' he admitted, 'but I do want to go right through.' The pain in Thomas's letter was palpable. He wanted more than anything to keep alive the possibility that he might come to New England at some later time. 'There is no one to keep me here except my mother,' he confessed. And he told Frost of his first sonnet: 'A month or two [ago] I dreamt we were walking near Ledington but we lost one another in a strange place & I woke saying to myself "somehow someday I shall be here again" which I made the last line of some verses.

A DREAM

Over known fields with an old friend in dream
I walked, but came sudden to a strange stream.
Its dark waters were bursting out most bright
From a great mountain's heart into the light.
They ran a short course under the sun, then back
Into a pit they plunged, once more as black
As at their birth; and I stood thinking there
How white, had the day shone on them, they were,
Heaving and coiling. So by the roar and hiss
And by the mighty motion of the abyss
I was bemused, that I forgot my friend
And neither saw nor sought him till the end,
When I awoke from waters unto men
Saying: 'I shall be here some day again.'

The roar and hiss and the mighty motion of the abyss seemed unmistakably war torn, and amid the din his friend would be temporarily forgotten, neither seen nor sought until the episode was done. It had been the greatest friendship of his life, but it had been challenged first by a gamekeeper and now by the notion of a road not taken, and Thomas dreamed of forgetting his friend. Curious that he should choose this moment to explore a sonnet for the first time, a form frequently employed for love poetry, and one which he had long loathed. 'I have a dread of the sonnet,' he had written in 1902. 'It must contain 14 lines and a man must be a tremendous poet or a cold mathematician if he can accommodate his thoughts to such a condition. The result is—in my opinion—that many of the best sonnets are rhetoric only.' He wrote just seven, and a handful of double and treble sonnets; but here the form had fitted the moment exactly.

Thomas's verse seemed naturally in tune with Frost in that week of his great decision. On 11 July he wrote the poem that Frost would describe as 'the loveliest of all', 'Aspens', after the whispering poplars on the crossroads at the Cricketers Inn, Steep; the next morning he wrote 'The Mill-Water', with its unmistakable tribute to Frost: 'The sound comes surging in upon the sense'. On 14 July Thomas took his army medical examination. He was seen along with six other men, stripped and measured together and made to hop around the room on each foot. He told the doctor nothing of the diabetes which he believed had begun to develop some time before 1914, and they did not spot it; he knew that had it been diagnosed it would have been grounds on which to reject him. And so he passed, and began the process of letting his friends know. At St George's Café that day, Edward Garnett was the first to receive the news, then Davies and Freeman. Jack Haines got the first letter, written that evening. 'I am enlisting. I passed the doctor today and go up on Monday to join the Artists Rifles and get turned (if possible) into an officer.' For Eleanor, he prepared a personal visit, calling at her mother's home on Fellows Road. 'I rose as he came into the room,' she wrote. 'He bent his head, and for the only time in our four years of friendship we kissed spontaneously. He sat down saying, "Well, I've joined up."' But to Helen, he broke the news by telegram, and left her alone in Steep with her despair: '''No, no no," was all I could say; "not that".'

On the morning of 19 July Thomas reported to 17 Dukes Road, near London's Euston station, to be attested Private 4229 in the 28th Battalion, The London Regiment (Artists Rifles). He swore his oath. 'I, Philip Edward Thomas, swear by Almighty God, that I will be faithful and bear true allegiance to His Majesty King George the Fifth, His Heirs, and Successors, and that I will, as in duty bound, honestly and faithfully defend His Majesty, His Heirs, and Successors, in Person, Crown and Dignity, against all enemies, according to the conditions of my service.' To swear before a god in whom he did not have faith, to a monarchy he had been brought up to believe was imperialist, and to defend their Person, Crown and Dignity (not People, Country and Culture): what was he agreeing to?

Thomas reported for physical drill at Regent's Park the next morning, six full hours of it, but it was hardly the start that he had been hoping for, as his new army boots pressed painfully at the still-sore tendon on his right foot and he had to be put on sick leave for the remainder of the week. 'Silly to be in uniform and useless,' he told Eleanor ahead of an appointment with the doctor. 'I only hope he won't give me leisure to think why I joined. Several people have asked me, but I could not answer yet.' To Bottomley he could offer only the haziest of explanations, pleading that it was not a desperate resolution, nor one with a particular purpose, 'but the natural culmination of a long series of moods and thoughts'. Laid up and out of action on his first week, Thomas spent the time writing poetry from his parents' house in Balham where he had been billeted, spending six hours 'perspiring' over ten lines. He began to look over his dreaded Marlborough proofs and, more pleasantly, spent the weekend catching up with friends in and around London. He wrote regularly to Helen, but did not return at the weekend to be with her in Steep. By now she had come to be glad of one thing at least: that there was to be no move to the States; she put her store instead in the hope that the war would be over long before Edward would be sent overseas. But at that moment his mind was tuned to confrontation, and he wrote eight lines of verse that seemed to serve as a call to arms:

COCK-CROW

Out of the wood of thoughts that grows by night
To be cut down by the sharp axe of light,—
Out of the night, two cocks together crow,
Cleaving the darkness with a silver blow:
And bright before my eyes twin trumpeters stand,
Heralds of splendour, one at either hand,
Each facing each as in a coat of arms:
The milkers lace their boots up at the farms.

'Here then ends reviewing & I suppose verses, for a time,' he told Gordon Bottomley. Indeed it did: it would be four months until Thomas felt prepared to face another poem.

* * *

Robert Frost had received the news from Edward Thomas of his enlistment. If there had been so much as a whiff of cowardice over the incident with the gamekeeper then it had been most certainly dispelled. From the farm in Franconia, New Hampshire, where he had moved in April, Frost wrote to Thomas in heroic terms. 'I am within a hair of being precisely as sorry and as glad as you are. You are doing it for the self-same reason I shall hope to do it for if my time ever comes and I am brave enough, namely, because there seems nothing else for a man to do.' Thomas would have chuckled affectionately at Frost's bluff and rhetoric, which seemed more closely aligned to the Frontier spirit than anything he would experience in the Home Counties training camps; but he would have appreciated the sentiment well enough. He was quite untroubled by the notions of masculinity that could entangle Frost at times, though he would have greatly valued the camaraderie which Frost now offered him. 'You have let me follow your thought in almost every twist and turn toward this conclusion,' Frost wrote. 'I know pretty well how far down you have gone and how far off sideways. And I think the better of you for it all. Only the very bravest could come to the sacrifice in this way.'

On Monday 26 July Thomas returned from sick leave to try again at army life. For the next two weeks he wondered if his tendon would hold up to the strain of daily drill, but hold up it did. Typhoid inoculations and poor sleeping left him feverish and weary by the week's end, however, and he was grateful when Vivian Locke Ellis offered to drive him from London to Steep and back in his new motor car on the weekend of 7-8 August; Mrs Ellis came too, and stayed on with Helen to offer her company. It was as much as Thomas could manage to walk gingerly up to the hilltop study with Bronwen, who chatted in her indefatigable way: did he have his uniform yet? what was the drill like? and a dozen other questions about his new life in the army.

Thomas's billeting at his parents' at Rusham Road, Balham was, predictably, causing strain and he anxiously awaited a transfer to camp. 'My father is so rampant in his cheery patriotism that I become pro German every evening,' he reported to Frost. 'We can never so beat the Germans that they will cease to remember their victories. Pom-pom.' The Defence of the Realm Act had been introduced days before, and anyone now speaking well of the enemy could expect a fine, even for a comment made at a private dinner party; Edward must have wondered wryly whether his father might be close to invoking it. Mercifully, he believed that he would be in the Artists Rifles camp at Epping Forest within the fortnight, and once there, expected three to four months of training before deployment. But this was guesswork, he admitted, for he had no sense of which regiment he might ultimately serve in or where his first commission might take him, and for the moment it did not much matter: 'one ceases to be curious'.

By the fourth week he was recovered and beginning to enjoy life again. 'I am a real soldier now,' he told Frost on 10 August. I stand very nearly as straight as a lamp post and apparently get smaller every week in the waist and have to get new holes punched in my belt.' His day began at six each morning, polishing his buttons and belt, his boots and his badge, before leaving Balham and heading across London to Dukes Road for physical drill. He enjoyed the exercise: the running, the battlefield training, even the leap-frog that the recruits were put through daily; but he found the society strained, as he told Jack Haines. 'The drills and lectures and marches are quite interesting, but not the men—they are the worst yet, quite impossible to make friends of and everyday acquaintances, and mostly cockneys, business men, clerks etc.' The regiment was populated by those with intelligent newspaper opinions and an interest in clothes, he thought—public school, literary or professional men—in short, those quite like himself with whom he could not get along. 'It is a question now whether I should have been worse off say in the Welch Fusiliers with a mixture of clerks and shop men and manual workers.'

The Artists Rifles formed in the middle of the nineteenth century as a volunteer group of writers, painters, musicians and engravers; Minerva and Mars were their patrons. They founded their headquarters in Dukes Road in 1880, one of twenty-eight volunteer battalions that combined to form the London Regiment. Dante Gabriel Rossetti had served with the Artists, as had Algernon Swinburne and William Morris. Paul Nash saw service there during the Great War, as would Wilfred Owen. Eventually, recruitment was limited by recommendation from serving members ('they let in anybody now who will pay 25/- a year subscription', Thomas complained), but for the time being it was a popular choice among university and public school graduates, who were frequently considered such capable officers that they were poached by other army units or chosen to set up Officers Training Corps. In excess of 10,000 officers were commissioned during the war after training with the Artists Rifles; the Royal Artillery alone took nearly a thousand. But they suffered appalling casualties: some 6,000 of the 15,000 serving Artists were killed, wounded or posted missing or captive.

As Thomas settled into life with the Artists, Edward Garnett had left for duty with the Ambulance Corps on the Italian Front. T. E. Hulme was returning injured from the Western Front, while John Masefield was serving as a hospital orderly and Ralph Hodgson in the anti-aircraft squadron patrolling the east coast of England. Abercrombie, Gibson and Drinkwater were in civilian clothes; Rupert Brooke was dead. Jack Haines reported he would go mad if he enlisted, but expected that he would have to anyway. Walter de la Mare was forty-two and would be beyond even the age limit for conscription when it was introduced in 1916. W. H. Davies and Gordon Bottomley were invalided. Harold Monro was 'in the country with his girl', said Thomas, apparently unaware of his efforts to enlist, while two other visitors to the Poetry Bookshop, Siegfried Sassoon and Robert Graves, were now serving in France. Wilfred Owen was still a civilian teacher, but he had now made his decision to enlist.

Edward Thomas had felt that none of his friends besides Frost had seemed willing to help his poetry forward that summer, but Lascelles Abercrombie now would. He was prospecting for an anthology of contemporary verse that he was hoping to co-edit for Constable, and when Bottomley showed him the poems that Thomas had sent him, Abercrombie agreed at once that they should be included. An Anthology of New Poetry would come out in March 1917, a month before Thomas's death; it would be the only time that he saw a selection of his work in print. Across the Atlantic, Robert Frost was toasting news which testified to the new readership that he was winning. 'The Road Not Taken' appeared in the Atlantic Monthly in August 1915. But if he mentioned this to Thomas then that particular letter has gone astray.

* * *

About the Author Matthew Hollis is the author of Ground Water, shortlisted for the Whitbread Prize for Poetry, the Guardian First Book Award, and the Forward Prize for Best First Collection. Now All Roads Lead to France is his first prose book. It was awarded the H. W. Fisher Best First Biography Prize and the 2011 Costa Biography Prize.